1. Field of the Disclosure
The present application relates to a display device. More particularly, the present application relates to an organic light emitting diode (OLED) display device capable of being bent in a curvature radius below 5 mmR.
2. Description of the Related Art
In general, liquid crystal display (LCD) devices, plasma display panels (PDPs) and organic light emitting diode (OLED) display devices have features of thinner, lighter weight, lower power consumption and lower driving voltage compared to cathode ray tubes (CRTs). As such, the LCD devices, the PDPs and the OLED display devices are being widely applied to a variety of appliances. Particularly, the OLED display devices have features such as high response time, high light emission efficiency, high brightness and wide viewing angle because of using self-illuminating elements.
The recent technical development allows flexible display devices to come into the spotlight as a new technology of a display field, instead of the rigid display devices employing glass substrates. The flexible display devices are implemented on a thin substrate such as a plastic substrate or others. As such, the flexible display devices can be folded or rolled as paper without any damage. Therefore, the flexible display devices are being actively developed as the next generation display device.
A flexible display device according to the related art must have a panel thickness not less than 300 μm due to functional films attached to its upper and lower surfaces. This panel thickness makes the flexible display device to be not bent physically below a fixed curvature radius. Due to this feature, however, the display quality of the related art flexible display device deteriorates.
A panel can be forcibly bent below the fixed curvature radius. In this case, a large quantity of blowholes can be generated when a laminating process of a cover window is performed later. Also, the panel can be separated from the cover window due to its elastic property.
To address this matter, it would be desirable to have a display device which is adapted to bend the flexible substrate and which has an enhanced display quality.